This invention relates to abrasive products.
Abrasive compacts are used extensively in cutting, milling, grinding, drilling and other abrasive operations. The abrasive compacts consist of polycrystalline diamond or cubic boron nitride particles bonded into a coherent hard conglomerate. The abrasive particle content of abrasive compacts is high and there is an extensive amount of direct particle-to-particle bonding. Abrasive compacts are made under elevated temperature and pressure conditions at which the abrasive particle, be it diamond or cubic boron nitride, is crystallographically stable.
Abrasive compacts tend to be brittle and in use they are frequently supported by being bonded to a cemented carbide substrate. Such supported abrasive compacts are known in the art as composite abrasive compacts. The composite abrasive compact may be used as such in the working surface of an abrasive tool.
Examples of composite abrasive compacts can be found described in U.S. Pat. Nos. 3,745,623, 3,767,371 and 3,743,489.
Other effective cubic boron nitride abrasive bodies which do not contain as high an abrasive particle content as abrasive compacts are also known and used in the art. Such abrasive bodies generally comprise a sintered body containing 40 to 60 volume percent of cubic boron nitride particles uniformly dispersed in a continuous ceramic bonding matrix. These abrasive bodies are also made under temperature and pressure conditions at which the cubic boron nitride is crystallographically stable. U.S. Pat. No. 4,469,802 describes such a body.
Recently there has been introduced on to the market a composite diamond abrasive compact under the trademark "claw cutter". This cutter has a diamond compact layer on the cemented carbide substrate and in addition a series of grooves formed in the substrate immediately behind the diamond compact layer and containing diamond compact. During use wear of the compact layer occurs and once this wear reaches the grooved zone, so it is said, sharpening occurs enabling a longer and more effective abrasive action to take place.
Composite abrasive compacts are generally produced by placing the components in powdered form, necessary to form an abrasive compact on a cemented carbide substrate. This unbonded assembly is placed in a reaction capsule which is then placed in the reaction zone of a conventional high pressure/high temperature apparatus. The contents of the reaction capsule are subjected to conditions of elevated temperature and pressure at which the abrasive particles are crystallographically stable.